<!DOCTYPE html>
<html>
<head>
  <title>error</title>
  <style type="text/css">
    .center {
    position: fixed;
    top: 30%;
    align:center;
   }

  </style>

    <script type="text/javascript">


</script>
</head>
<body>
  <div  class="center" align="center">

      <button onclick="window.AndroidWebView.checkVersion()">版本更新</button>

</div>
</body>
</html>